The present invention relates in general to a method and apparatus for delivering ablative laser energy and determining the volume of tumor mass destroyed, and in particular to a method and apparatus for determining the volume of tumor mass destroyed by a minimally invasive treatment, such as interstitial laser therapy, such that a graphical representation of the destroyed tumor mass can be displayed for real-time visual monitoring of the destruction of tumor mass.
Percutaneous in situ or on-site treatment of malignant breast tumors by laser therapy is being developed in part due to the fact that breast cancer is being detected at earlier stages because of the increasing number of women receiving mammograms annually. If breast cancer and other cancers or tumors are detected in early development, the tumor can be effectively treated using an ablative agent such as laser energy.
Image-guided laser treatments of malignant tumors such as, breast, liver, head and neck tumors, have been in development for more than a decade. For example, U.S. Pat. No. 5,169,396 (xe2x80x9cthe ""396 Patentxe2x80x9d) issued to Dowlatshahi is directed to the interstitial application of laser radiation therapy to tumor masses and is incorporated herein by reference. In general, the apparatus of the ""396 Patent includes a probe having a thin metallic cannula for insertion into a tumor mass, a laser for generating light having a chosen wavelength and intensity, and an optical fiber for receiving and transmitting the laser light to the tumor mass, whereby the optical fiber is inserted into the cannula such that a chosen physiologically acceptable fluid can flow coaxially between the cannula and the optical fiber. In addition, a heat sensing member is inserted adjacent into the tumor mass for monitoring the tumor temperature. The devitalized tumor is gradually cleared by the body immune system and within six months is replaced with a scar.
However, the treatment of tumors and in particular the specific treatment of breast tumors is generally known to be more difficult due to the fact that it is difficult to determine the three dimensional boundaries of the tumor, and thus, difficult to determine when all of the tumor has been destroyed.
To address this problem, medical researchers have utilized a variety of tumor mass identification techniques for determining the size and outer boundaries of a tumor mass. Examples of conventional identification techniques that have been employed in combination with laser therapy are magnetic resonance imaging, radiographic and sonographic techniques. When utilizing an identification technique, coordinates identifying the actual size of the tumor mass are determined by using stereotactic techniques or the like.
To solve this problem, at the time of laser treatment, markers may be placed in a 0.5-1.0 cm zone of xe2x80x9cnormalxe2x80x9d tissue to demarcate the zone in which the tumor extension may exist. This ring of xe2x80x9cnormalxe2x80x9d tissue is equivalent to a cuff of tissue engulfing the tumor removed during conventional surgery (i.e., a lumpectomy). The boundaries of the ring surrounding the tumor are marked at 3, 6, 9 and 12 o""clock locations by inserting metal markers through a needle. The insertion points are precisely determined by known stereotactic technique using a commercially available stereotactic table.
Such marker elements are the subject of U.S. Pat. No. 5,853,366 (xe2x80x9cthe ""366 Patentxe2x80x9d) issued to Dowlatshahi is directed to a marker element for interstitial treatment. In general, the ""366 Patent discloses a marker element that can be positioned wholly within the body of a patient by utilizing a guide member having a guide path so as to mark a tumor mass of interest. The marker element is made of a radiopaque material which includes any material that is capable of being detected by conventional radiographic, sonographic or magnetic techniques.
Medical researchers have also employed non-surgical techniques other than laser therapy to treat breast tumors. For example, radio frequency, microwave, and cryogenic-related treatments have been attempted.
The present invention recognizes the above described problem, that is, to provide a non-cutting treatment for cancer and in particular for breast cancer that can be relied upon to determine when the entire tumor is effectively destroyed. There is accordingly a need for a non-cutting breast cancer therapy which addresses this problem and the problems arising from the difficulty in determining whether the tumor is completely destroyed.
The present invention solves the above problems by providing an apparatus and method for determining a volume of tumor mass (such as breast cancer) destruction in tissue mass (such as breast tissue) within the body of a patient such that a graphical representation of the destroyed mass can be preferably superimposed onto an image of the actual tumor mass whereby the destruction of tumor mass can be visually monitored in real-time. The preferred embodiment of this invention is described in conjunction with breast tissue and breast cancer or tumors, although it should be appreciated that the present invention may be adapted to be implemented for other tumor or cancer treatment. The preferred embodiment of the present invention is also implemented with a patient positioned on a commercially available stereotactic table. The invention may alternatively be implemented using ultrasound and magnetic resonance imaging (MRI) techniques, provided that the tissue mass such as the breast is immobilized and the target is fixed.
The apparatus of one embodiment of the present invention preferably includes a laser gun. The laser gun is adapted to receive a laser probe having a temperature sensor thereon and a temperature probe having a series of temperature detectors thereon. The laser gun inserts the laser probe into the tumor mass to facilitate providing an effective amount of laser radiation and measuring the tumor temperature at the application point of the laser. The gun also subsequently inserts the temperature probe into the body preferably in close proximity of the tumor mass. The temperature probe measures the body or tissue temperature at various locations in proximity of the tumor mass during interstitial laser therapy. The laser probe and temperature probe preferably include position marks to enable the operator to precisely position and determine the position of the probes relative to each other.
The apparatus preferably includes a computer control system that is electrically connected to the laser gun and its components, namely, the laser probe and sensor and the temperature probe and detectors. The computer control system determines the volume of tumor mass destroyed by utilizing operational data, such as, the distance between the temperature sensors, temperature data, that the control system receives from the laser probe and temperature probe. The computer control system calculates the volume of tumor mass destroyed at any given time during the interstitial laser therapy based upon the tumor mass temperature and the body or tissue mass temperature surrounding the tumor mass.
As the computer control system calculates the volume of tumor mass destroyed, the computer control system displays sequential graphical representations of the amount of destroyed tumor mass which is superimposed onto an image of the actual tumor mass in real-time. This graphic display thereby enables doctors to visually monitor the amount of tumor mass destroyed in real-time during the interstitial laser therapy such that the user can determine when the tumor mass destruction is effectively complete.
It is therefore an advantage of the present invention to provide an apparatus and method for calculating the volume of tumor mass destruction such that a graphic representation of the destroyed tumor mass can be displayed.
It is another advantage of the present invention to provide real-time visual monitoring of the destruction of tumor mass during laser therapy.
It is a further advantage of the present invention to provide an apparatus and method for determining when the destruction of tumor mass is effectively complete.
It is still further an advantage of the present invention to provide an apparatus and method for determining when the destruction of a breast tumor mass is effectively complete during interstitial laser therapy.